In recent years, from the viewpoints of both energy problems and environment problems, not only converting the renewable energy such as sunlight into the electric energy to utilize it, but also converting it into a storable and conveyable state is highly desired. In response to this demand, research and development on an artificial photosynthesis technology that produces chemical substances using the sunlight like the photosynthesis by plants are in progress. This technology also creates a possibility of storing the renewable energy as a storable fuel and further, produces chemical substances to be industrial raw materials, and thereby, creation of value is also promising.
As a device that produces the chemical substances using the renewable energy such as the sunlight, there has been known an electrochemical reaction device that includes a cathode to reduce carbon dioxide (CO2) from, for example, a power plant and a waste treatment plant and an anode to oxidize water (H2O). The cathode reduces carbon dioxide to produce a carbon compound such as carbon monoxide (CO), for example. When such an electrochemical reaction device is fabricated by a cell form (to be also referred to as an electrolysis cell), fabricating the electrochemical reaction device by a form similar to a fuel cell such as a Polymer Electric Fuel (PEFC), for example, is considered to be effective. However, in this case, a problem similar to a problem that the PEFC has is sometimes caused.